Reactive oxygen species, calcium and serine/threonine phosphatase are required for copper-induced MAP kinase gene OsMAPK2 , expression in rice

Regulation of the MAP kinase gene (OsMAPK2) expression in rice under metal, copper, stress conditions was investigated. OsMAPK2 transcript accumulation was enhanced by copper and H2O2 in rice root-tip cells. To investigate how the OsMAPK2 gene is regulated in response to copper, inhibitor studies were performed. Using Northern blot analysis, it was shown that antioxidant agent (GSH), calcium chelator (EGTA), plasma membrane calcium channel blocker (La3+) and protein phosphatase inhibitor (cantharidin) inhibited copper-induced OsMAPK2 gene activation. We suggest that the stimulation of OsMAPK2 transcript accumulation by copper in rice roots operates may through an intracellular signalling cascade mediated by reactive oxygen species, extracellular calcium ions and cantharidin-sensitive protein phosphatase(s).